chore(deps): update sigstore/cosign-installer digest to c6d50c2

Author: renovate[bot]

.github/workflows/relay.yaml

@@ -36,7 +36,7 @@ jobs:
 
       - name: Install cosign
         if: github.event_name != 'pull_request'
-        uses: sigstore/cosign-installer@7e0881f8fe90b25e305bbf0309761e9314607e25
+        uses: sigstore/cosign-installer@c6d50c2e98b401591ef0ec04be0868d8f2626d0f
         with:
           cosign-release: 'v1.4.0'